Your Complete Guide to Menstrual Blood Clots

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Your Complete Guide to Menstrual Blood Clots

Your Complete Guide to Menstrual Blood Clots

Do you feel like there's a crime scene in your pants? Don't worry, we're here to dive deep into everything about blood clots during menstruation. What are these little things, why do they happen, what should you be aware of, and when should you talk to a medical professional? Let's untangle it all for you.

Our bodies are amazing and unique. Every person's menstrual cycle is different, which is great, but it can also lead to various issues, especially when it comes to menstrual blood and clots. So, what causes menstrual blood clots, and should you be concerned about them? Beautikini has compiled a guide to help you accurately understand what normal menstrual blood clots are and the possible reasons behind them. Read on for more details here.

What are menstrual blood clots?

Have you ever noticed thick "clots" during your period? These are menstrual blood clots, composed of coagulated blood and tissue. While they might sound concerning, they are actually completely normal for most women and individuals who menstruate. In fact, in most cases, clots indicate everything is normal.

Imagine a gummy strawberry melting in the sunlight. Or one of those chunky bits you find in a jar of jam.

They can range in color from bright red to darker hues, and normal clots are usually no larger than a penny and don't occur frequently.

What causes menstrual blood clots?

Blood clots occur when menstrual blood (a mixture of blood, tissue, and mucus) accumulates within the uterus, awaiting contractions of the uterus to expel it from the body.

Typically, the body releases anticoagulants to thin the mixture for easier passage; however, if the body can't do this fast enough, menstrual blood will accumulate within the uterus.

Because our blood contains tiny cells called platelets and clotting factors. When blood vessels are damaged, platelets gather at the site of injury and, together with clotting factors, form a clot to stop bleeding. During menstruation, when the uterine lining sheds, blood vessels within the uterus bleed. If blood pools in the uterus or vagina, clots form due to this mechanism.

Rest assured, it's all very normal, especially in the first two days of menstruation when blood flow is highest.

What do menstrual blood clots look like?

The size, thickness, and color of menstrual blood clots can vary. If you've been tracking your cycle and know what's normal for you (check out our menstrual blood color guide), you may have noticed some clots during your period.

Of course, everyone's body is different, so as a general guide, menstrual clots typically fall into one of the following categories:

Normal menstrual clots

Normal clots can range in color from bright red to dark red and have a thick, almost jelly-like consistency. They're usually no larger than 2 centimeters and primarily occur on the heaviest days of bleeding. Similarly, tracking your period can help you understand your flow, and you might know when to expect heavier bleeding.

Brown blood clots during menstruation

Brown clots are nothing to worry about. They may occur towards the end of your period as blood flow slows down, taking longer to leave the uterus. The longer blood stays in the body, the darker its color becomes.

This is why you might also see brown clots at the beginning of your period. It's just your body getting rid of "old" blood from the previous cycle.

Small blood clots during menstruation

Small clots are generally nothing to worry about, and many women encounter them during their period. Most normal clots are about 2 centimeters in size. As a general guide, the National Health Service recommends not worrying if they're no larger than 10 pence coins.

Normal Blood Clots vs. Abnormal Blood Clots

While most menstrual blood clots are entirely normal, it's always worthwhile to understand abnormal clots and what they may signify for you. Being able to discern between normal occurrences and potential issues is meaningful.

Abnormal menstrual blood clots aren't always cause for alarm, but in rare cases, they may indicate a problem that needs to be checked by a doctor. Here are some situations that could be underlying causes of excessive menstrual blood clots:

Uterine polyps or fibroids

These can lead to blockages in the uterus, preventing it from contracting properly. When this happens, it can't expel blood as it should, so blood exits the vagina slowly, meaning there's more time for larger clots to form.

Uterine polyps and fibroids are non-cancerous, but if left untreated, they can lead to other health issues. They typically consist of endometrial tissue or muscle tissue growing within the uterine wall, which may cause back pain, pain during intercourse, bloating, fertility issues, and clotting.

Endometriosis or adenomyosis

Endometriosis is a major culprit for painful periods and excessive bleeding as tissue from the uterine lining grows outside where it should. This often leads to various symptoms, including pelvic and/or lower back pain and cramping, heavy or painful periods, pain during intercourse, and fertility issues. Similarly, adenomyosis causes similar problems and can also lead to menstrual clotting.

Enlarged uterus

If your uterus is slightly larger than before due to recent childbirth, it provides more space for menstrual blood to accumulate. This can lead to clotting.

Bleeding disorders

If you have bleeding disorders, you may experience excessive menstruation as the endometrium doesn't always allow for clotting as it should. Conditions like platelet function disorders or von Willebrand disease (VWD) can lead to abnormal menstrual bleeding and clotting.


While abnormal clots should be checked by a GP early, they aren't considered a medical emergency unless you're experiencing severe pain.

Mild bleeding during pregnancy is common but should still be checked by a doctor. However, if you're experiencing heavy bleeding and clots during pregnancy, you should seek immediate medical help as this could be a sign of miscarriage.

It's also worth noting that clotting abnormalities can lead to other health complications, such as iron-deficiency anemia. Your doctor will help determine if treatment is needed and may recommend specific tests to better understand what's happening. Excessive menstruation and clotting are definitely not something you should just endure, so be sure to seek advice.

Using Period Underwear to Manage Blood Clots

One of the biggest complaints among women experiencing heavy menstrual flow is the need for constantly changing sanitary products, even doubling up on pads and tampons during the heaviest days of their period. Having to change period protection every 1-2 hours or experiencing leaks onto underwear or bedding can indeed have a negative impact on your daily life—not to mention the economic burden it brings!

If this sounds familiar, then reusable period underwear might be the solution you're looking for. They completely eliminate the need for pads and tampons, and many find they can go longer between changes.

Our Beautikini Period Underwear can hold up to 40ml of blood, equivalent to 8 regular tampons (different styles have different absorbency levels).


If you're dealing with blood clots during your period, Beautikini Period Underwear can truly change the game, allowing you to go about your daily activities stress-free. If you have any questions, feel free to reach out to us, and we'll be happy to assist you!

Increased plasma clot permeability and susceptibility to lysis are associated with heavy menstrual bleeding of unknown cause: a case-control study - P Szczepaniak, M Zabczyk, A Undas - PLoS One, 2015 - journals.plos.org

Determinants and assessment of menstrual blood flow - J Liang, F Ali, M Ramaiyer, MA Borahay - Current epidemiology reports, 2023 - Springer

Heavy menstrual bleeding: an update on management - J Davies, RA Kadir - Thrombosis research, 2017 - Elsevier

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